Chromosomes

So X tells me to say hello to Y. Y is X's former girlfriend.
Of course i will, i tell him.
But as he leaves i realize how familiar this scenario is: if i tell Y that X says hello, she will say "oh, that bastard. Tell him that next time he wants to say hello, he could at least pick up a phone and do it himself". And if then X asks what Y said, i will have to answer the truth and he will think or say out loud "why do i even bother?".
Otherwise i can just keep quiet about it in the first place. Never tell Y that X says hello. Problem temporarily solved.
Temporarily.
But what if then X asks me what she answered? Can i say "oh sorry i didn't tell her"? Of course not! So i can choose between telling him that she says hi back, or telling him oh-that-bastard-etc. anyway.
Both these last two options would bring disaster: X would either decide to call Y inspired by a fictitious good response, or continue carrying a grudge due to her fictitious-but-realistic (because as i said earlier, i know how these things go) response.
So i have two options, each with two possible solutions. And all four of these solutions would be disaster.

Current opinion: not telling Y that X says hello. Unless of course conversations with her get particularly boring.
Because after all, why do i even bother?